The Mexican blind brotula (''Typhliasina pearsei'') is a species of

viviparous brotula The viviparous brotulas form a family, the Bythitidae, of ophidiiform fishes. They are known as viviparous brotulas as they generally bear live young, although there are indications that some species (at least '' Didymothallus criniceps'') do no ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, where it is found in

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

s and

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

s. It is known as ''sak kay'' in

Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken ...

and ''dama blanca ciega'' in

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...

. This

cavefish Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish and ...

grows to a standard length of . It is the only known member of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Description

The Mexican blind brotula has a large, laterally compressed, scaleless head with no eyes, but several papillae and cavities which contain sensory organs. The nostrils are located on the upper lip and the mouth has a longitudinal split at the back. The body bears scales and has long dorsal and anal fins which terminate close to, but are separate from, the caudal fin. The dorsal fin has no spines and 75 to 87 soft rays, and the anal fin has no spines and 59 to 68 soft rays. The male has two pairs of pseudoclaspers, the inner ones being in front of the outer ones. The standard length is about . The skin does not contain pigment, making the fish appear pinkish-white.

Distribution

The Mexican blind brotula inhabits the ''

cenote A cenote ( or ; ) is a natural pit cave, pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly ...

s'' (water-filled sink holes) and

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...

s in the

Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán ) is a large peninsula in southeastern Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north ...

of Mexico, where the temperature is between throughout the year. These are typically anchialine (connected to the sea), but the Mexican blind brotula is only known from the sections with fresh or

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estu ...

water.

Ecology

The Mexican blind brotula is the top predator in the Yucatán aquifer system and is probably not very numerous. It feeds on crustaceans such as shrimps and

mysid Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in ...

s that also inhabit the aquifers. In some locations, it is associated with another blind fish, the blind swamp eel (''Ophisternon infernale'') and in one cave system, with the catfish ''

Rhamdia guatemalensis ''Rhamdia'' is a genus of three-barbeled catfishes found in Mexico, Central and South America. These catfishes are nocturnal, opportunistic carnivores, found in a wide range of freshwater habitats. This genus includes a number of troglobitic me ...

''. It does not react to light, but is very sensitive to vibrations. It is a

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

fish, giving birth to up to a dozen young between December and February. The newborns are yellowish and about in length.

Status

The main threat faced by this fish is from water pollution; the aquifers in which it lives are below inhabited areas with inadequate sanitary arrangements, so that

coliform bacteria Coliform bacteria are defined as either motile or non-motile Gram-negative non- spore forming Bacilli that possess β-galactosidase to produce acids and gases under their optimal growth temperature of 35-37°C. They can be aerobes or facultative ...

may leak in, and excess nitrates may be in wastewater. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

has rated the conservation status of this fish as being "

near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify f ...

Etymology

The generic name derives from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''typhlos'' meaning "blind" and the specific name honours the American

ecologist Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

, Arthur Sperry Pearse (1877-1956), who was the collector of the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

used by Carl Leavitt Hubbs to describe the species.

References

External links

* {{Taxonbar, from=Q5306904 Bythitidae Cave fish Monotypic fish genera Endemic fish of Mexico Freshwater fish of Mexico Taxonomy articles created by Polbot Fish described in 1938 Taxobox binomials not recognized by IUCN